Apparatus for forging crank-shafts and like work-pieces



March 25, 1958 G. s. CLEGHORN 2,327,685

APPARATUS FOR F ORGING CRANK-SHAFTS AND LIKE WORK-PIECES Filed June 25, 1953 /5 M //b 1/ ,5 as 5b 26 72 12 12a 3 5 D 4b 12 Q 8a 4a United States Patent 6) lei This inventionrelitesto air improvement iii apparatus for-forging crank shaft sanddikeWork-pieces of the kind ds'c'rihed in" rior- United Statesspecification N6. 2,534j6l3f In the aforesaid prior specification, there is disclosed: an'apparatus, which can be 'utilisedinconjunction with: an ordinaryforging"press;-.for the purpose of'forging, crank 'shafts and other fwork pieces having enlarged parts;- separated by'jeccent'ri'c orconcentric constructions Siich work pieces'are' forged'froin blanks provided with-swellssparat'edby constrictions'or from blanks'of plane,=-.cylind rical or other shape dependingnpon thewfinal 'shape-to be obtained, the'inter'calary parts-of the blanksimer parts'whi'ch"do-nothave to undergo considerable defer matiomdu'ring the forging operation, having shapes and-- .h 0 dlmenslons to allow their ZCCOmmOdElIOILJH- (1168' SUIT-1'" ablyrecesse'd for the purpose. The apparatus-format ryingiout the forgingoperation is constituted by end dies which "receive' the extremities of the blank and-by;two-.- central half dies which act transversely for the displacement of the middle intercalary part of. the blank', .the end dies having their movements related to those of the central die by meansoframps 'insuch a way that the end dies I ensure: the upsetting or longitudinal forging ofjthe blank while the central die-displaces' the middle-inter calar'y part;

In 'the 'afores'aid apparatus the movements of the cen-i tral die "are cO-ordinated with the respective end dies "by separate: rampi means each ofwhich includes inclihed co-operating surfaces. In order to ensure even distribution of load on each end die it is therefore essential that the-ramps are-machined. and fitted with: great accuracy. In addition, the rubbing friction which necessarily occurs between the ramp surfaces not only causes wear necessitating frequent renewal of these surfaces, but also absorbs an appreciable amount of the power of the apparatus which could otherwise usefully be employed in the forging operation.

A main object of the present invention is to avoid the foregoing disadvantages in a manner which increases the efiiciency of the apparatus whilst at the samev time a simplifying and reducing the cost of manufacture.

According to the present invention, there is provided an apparatus of the kind specified wherein movement of the central die during a working stroke is transmitted to the end dies by link means which are adapted and arranged to exert an increasing pressure on said end dies towards the end of the working stroke.

According to a more limited aspect of the invention there is provided an apparatus for forging crank-shafts and like work-pieces from blanks, comprising end dies adapted to receive the extremities of a blank and acting to effect the upsetting or longitudinal forging of the said blank and two central half dies acting transversely for the displacement of a middle intercalary part of the blank which does not have to undergo any considerable deformation during the forging operation, the said cen- Patented Mar. 25, 1958::

tral-halfidiesbeing-aetuated by' a-reciprocable"crosshead of 'the-'apparatus 'and the said end dies having their move ments' related" to those of'the central diebyrneansof links which: are adapted and'arranged to exert an increas-i ing pressure -'on 'saidend dies towards the end of the work ing stroke pf the crosshead.

In order that the invention may" be'clearly understood and readil'y'carriedinto effect, one "embodiment thereof will now be desc'ribed -'in' detail with reference to the accompanyiiig'pa-rtially diagrammatic drawings from which parts-of known constructiomhaving .no"direct"bearing. on: the "present-invention have been omitted for'thesake' of'cl'arityi" Inthe drawings,

Figure l is'a" roken "section'p'artly along the longitudifiaFcentralaxisofthe apparatus and partly'alongthe lihe' B B "of Figure 2, and

F1 nre-2'is an end elevation" of the apparatus partially. inse'cti'on"on'thelineA -A'of'Figure 1 'and partially. in section on the line DD of Figure 1.

The apparatusfas'illustratedhas a-b'ase or bed 1 the upper'surface'ofWhic'h is shapedto provide slideways ZI onwhich canslitie 'two cradles 3'. Also mounted on the bed- 1 approximately"centrally; is' the lower halfofa centr "die"shown diagrammatically at 4a. This-lower, halfdieiisicarrie'd by'a hydraulic tpistonandcyliiider as-. sembly' whicli" is again shown diagrammatically, at s.- Push back hydraulic pistons are also provided,'in known manner; in. the bed for returning, the half 'die 4a to its starting position after a 'forgingloperation, but thesetpisl-itons" form no-par't of the present inventionfandiareanot shown in the drawings Two lateral hydraulic. push back pist'ons '6 are associated with each cradle=3flfor-the purpios'e'of'returning the latter to their startinggpositionsa afterfaforginggoperation, these pistons 6Ioperating, in. cyl-: inde'rs'o'a formed inthe bed ll and being.,.coupled.-to: therespective cradles by; bracket plates 7." i

Thesliding cradles 3"each carry an-endtdie having am upper part 8 'and aseparatetlower partt8a; When-forgeing a crank shaft for example, these-end-dies serve tore ceiverespectivelythe parts of theblank -situatedonteither side' of "thatwhich" is to form the crank-throw The: parts 8, 8a of the end dies are separable by means'of hydraulicpush= back pistons 9- operating, invcylinders. 9a in a vreciprocable crosshead 10 of-theapparatus, .there -be ingdwo .such pistons '9 associatedawith theupperhal-fI S of 'each' end di. For the pur-pose 'of clamping, theuendw die parts together, with portions of a blank gripped therebetween, there are provided two hydraulic pistons 11 operating in cylinders 11a in the crosshead 10, there being 0 one such piston 11 associated with each upper part 8 of an end die. The pistons 11a are connected with the respective upper parts of the end dies by means of a slide block 11b on each piston which engages a slideway 8b on the top of the associated end die part 8.

The crosshead 10 also carries, approximately centrally, the upper part of the centre die shown diagrammatically at 4b.

For the purpose of co-ordinating the movement of the end die cradles 3 with the centre die 4a, 4b, during lowering of the crosshead 10, there are provided pairs of parallel link arms 12 between the crosshead and each end die cradle 3. Two pairs of link arms 12 are associated With each end die cradle, one such pair being located on either side of the supported end die. The link arms 12 are hingedly secured at their upper ends to hinge pins 13 mounted in hearings in the crosshead 10. Four such pins 13 may be provided, as shown, extending across the crosshead'10 in parallel relationship, each pin 13 carrying one link arm 12 from each of the two pairs of link arms associated with the underlying cradle 3. Alternatively, eight hinge pins may be appropriately mounted in the crosshead, each pin carrying'a single link arm. Thehin ge pins 13 extend transversely to the path of movement of the end dies and, extending parallel to these pins 13, are bearingpins 14 which are' secured to the respective cradles 3. yThesle bearing pins 14 are located 7 so thateach pin 14 has the lower end 124 of a link arm bearing-thereon. f The pins 14 are arranged to pivot in re-.

lation' to'the cradles @by whichthygare carriedand; to facilitate engagement with the lower; end ,124 of the respective linkvarrns, these latter arm ends are formed with av-shaped groove and the'seating'sur face of each bearing pin 14 is formed with a corresponding V-section.v

The location of the hinge and bearing pins 13, and 14 and the length of the link arms 12 is such that the link arms all incline inwardly from their upper ends direction of the longitudinal blank axis, the provision of motion transmitting means between said cross head and end dies comprising at least two pivotal thrust arm mountings located on said cross, head one on each side of the central die, thrust arms which depend respectively from said mountings at an inward inclination towards said central-die stop means on said cross head for determining the angular positions of rest occupied by said towards the" central die 4a, 4b. The link arms 12 of,

each pair of links thus constitute. two ot a parall elogram which is completed by parallellines passing through the'pivotal axes of the associated hinge. and bearing pins.

I Each cradle 3 is thus controlled by two such linkage 'parallelograms whichoperate in planes parallel to each other. c 7

V The zero or free position of the link arms 12 is determined by suitable stops 15 which, .in this example, are integral with'the crosshead 10; If desired, however, the stops 15 could be made adjustable. As an example, the link arms 12 of each pair may be inclined inwardly from their upper ends at some 49-45 "V to the horizontal when the associated end dies and cradles are fully with- 30 drawn as shown in Figure 1.

In operation, when the forging press is set in motion to lower the crosshead 1t and operate the central, die 4a,

4b, the link pairs serve to press the cradles 3 and end' dies 8, Sb'carried thereon inwardly in synchronism with the movement of the crosshead i 10. As the crosshead moves further down On its working stroke and the link arms 12 press the associated'cradles further along their slideways 2 towards the central die' 4a, 4b, thecangular position of the individual link arms 12 approaches closer to the horizontal whereby an increasing horizontal force component is obtained as the working stroke proceeds. This horizontal force component will, of course, reach its maximum towards the end of the working stroke which is just when the maximum upsetting effect on the blank being forged is required. V

"Iclaim: Y r

a 1. In an apparatus for forging crank-shafts fromblanks in which a transversely acting central die actuated by a reciprocable cross head operates in synchronism with movable end dies which approach one another in the pins each having a seating thrustarms when the cross head is withdrawn and pivotal seatings on the respective end dies positioned to receive the lower arm ends when the cross headis carrying out downward working stroke and the end dies are in the withdrawn position, the arrangement being such that said end'die's will be caused by, said thrust arms to approach one another under anincreasing force component as the working stroke proceeds. s, a

2. Motion transmitting means as claimedin claim'l in which four thrust armsare associated with each said end die, said four arms being tarranged in pairs with the arms of eachcsaid pair; constituting two opposite sides of a parallelogram linkage which is completed by parallel lines passing respectively throughthe centres of pivotal mountings of the pair of arms and through the centres of the pivotal seatings of said pair of arms and in which the lower end of each arm is formed with'aV-shaped seating recess and the 'seatings for the lower arm ends are in the form of laterallyprojecting pivotally mounted 7 surface formed with a corresponding V-section. s

3. Motion transmitting means as claimed in claimiZ includingradjustable' stops on said cross head for detert mining the angular position of rest of said thrusttarmsl when said'cross head is raised whereby said thrust arms will automatically engage their respective seatings. asso-' ciat'ed with the end dies when the cross head is lowered t on a working stroke from the starting position of the apparatus. w

keferenees Cited in the file of this patent, 

